Electron microprobe study of turquoise-group solid solutions in the Neyshabour and Meydook mines, northeast and southern Iran

ABSTRACT Turquoise, CuAl6(PO4)4(OH)8·4H2O, belongs to the turquoise group, which consists of turquoise, chalcosiderite, aheylite, faustite, planerite, and UM1981-32-PO:FeH. In order to study turquoise-group solid solutions in samples from the Neyshabour and Meydook mines, 17 samples were selected and investigated using electron probe microanalysis. In addition, their major elements were compared in order to evaluate the feasibility of distinguishing the provenance of Persian turquoises. The electron microprobe data show that the studied samples are not constituted of pure turquoise (or any other pure endmember) and belong, from the chemical point of view, to turquoise-group solid solutions. In a turquoise–planerite–chalcosiderite–unknown mineral quaternary solid solution diagram, the chemical compositions of the analyzed samples lie along the turquoise–planerite line with minor involvement of chalcosiderite and the unknown mineral. Among light blue samples with varying hues and saturations from both studied areas, planerite is more abundant among samples from Meydook compared with samples from Neyshabour. Nevertheless, not all the light blue samples are planerite. This study demonstrates that distinguishing the deposit of origin for isochromatic blue and green turquoises, based on electron probe microanalysis method and constitutive major elements, is not possible.

Перестройка спектров электролюминесценции в гетероструктурах II типа n-InAs/n-InAsSbP

Single heterostructures of type II n ^+-InA s/n ^0-InAs_0.59Sb_0.16P_0.25, based on an intentionally undoped epitaxial layer with an electronic type of conductivity are obtained by metalorganic vapor phase epitaxy (MOVPE). In the heterostructure, a transition layer of modulated composition is formed near the heterointerface in the bulk of the quaternary solid solution. The existence of a radiative recombination channel due to the presence of localized hole states in quantum wells formed in the transition layer near the heterointerface is shown. It is demonstrated that the maximum of the intensity of the electroluminescence spectrum of the heterostructure under study is rearranged when a forward external bias is applied. The results of this study can be used in the development of tunable light-emitting diodes operating in the midinfrared range of 2–4 μm.

A novel quaternary solid solution photo-absorber material for photoelectrochemical hydrogen generation

We report a novel quaternary solid solution (Ag–Cu–Sb–S or ACSS) serving as a photo-absorber material in the photoelectrochemical field for the first time, and ZnO/ACSS nanoarrays exhibited a photocurrent density of 4.45 mA cm−2.

Far-infrared dielectric function and phonon modes of spontaneously ordered (AlxGa1-x)0.52In0.48P

ABSTRACTWe present a far-infrared spectroscopic ellipsometry study of the phonon properties of partially CuPtB -ordered (AlxGa1-x)0.52In0.48P with x =0, 0.32, 0.7, and 1.0 and degrees of ordering η = 0 … 0.63, determined from generalized ellipsometry measurement of the near-band-gap order birefringence. An anharmonic oscillator approach is used to model the ordinary and extraordinary dielectric functions and determine the infrared-active longitudinal and transversal phonon modes of the thin film samples. Besides the isotropic GaP-, InP- and AlP-like phonon modes, we observe alloy-induced modes with low polarity for η ∼ 0. The evolution of lattice like and alloy-induced modes with increasing η is reviewed for Ga0.52In0.48P. With increasing η all phonon modes split in E- and A1 -type vibrations with polarization perpendicular and parallel to the sublattice ordering direction, respectively, and the mode frequencies shift continuously. Our observations extend recently published phonon frequencies from experiment and theory for CuPt-ordered Ga0.52In0.48P, which are compared and discussed. The phonon modes of highly ordered (AlxGa1-x)0.52In0.48P, η ∼ 0.6, are compared to the modes observed in the highly disordered quaternary solid solution. We propose the far-infrared dielectric anisotropy as a sensitive measure for sublattice ordering in multinary III-V alloys.